Fluid flow indicator



Aug. 29, 1950 F. N. WINDSOR 2,520,869

FLUID FLOW INDICATOR Filed Sept. 1, 1948 7 52 .14 INVENTOR.

FREDERICK N (MM/0:01P

Patented Aug. 29, 1950 .:U,NlTED- STATES PATENT OFFICE g rpo nrnow INDICATOR I JFrederick NrWindsor, Penn Township, Allegheny i County, Pa., assignor to Mine Safety Appliancesw Company, Pittsburgh, Pa., a. corporation of Pennsylvania 'i.Application September 1, 1948,:Serial'No.47,183:

This invention relates to apparatus for indieating to an observer when a fluid is flowin through afl'uidline.

I It is among the objects of this invention to provide a fluid flow indicator which shows at a glance whether or not fluid is flowing through a line, and which is very sensitive to the flow of fluid so that it instantly indicates starting or stopping of the flow.

In accordance with this invention a housing is provided with a fluid passage through it having an inlet and an outlet for connection in a line which carries the fluid, the flow of which it is desired to indicate. The housing has an observation opening extending laterally from the side of the passage to the outside of the housing, and a Window is sealed in that opening to keep fluid from escaping through it. Slidaby disposed in the housing passage is a slide which blocks the passage when the slide is located back between the observation opening and the passag inlet. The slide is held in that position by a spring when fluid is not flowing through the housing. When fluid is withdrawn from the passage outlet the pressure of the fluid against the other end of the slide pushes it forward against the resistance of the spring until the slide is in view through the window. The housing is provided with a by-pass which, when the slide is in its forward visible position, conducts fluid past the side in the passage. The by-pass may be formed by the inner end of the observation opening, and the slide may be provided with by-pass openings which the housing by-pass connects. Consequently, the presence of the slide in its forward position indicates that fluid is flowing through the housing.

The preferred embodiment of the invention is shown in the accompanying drawing in which Fig, I is a longitudinal section through my flow indicator when nothing is flowing through it; Fig, 2 is a transverse section taken on the line III--III of Fig. 1; and Fig. 3 is a view similar to Fig. 1, showing the position of the slide when fluid is flowing through the housing.

Referring to Figs. 1 and 2 of the drawings, two tubular members I and 2 are disposed in axial alignment with their adjacent ends encircled by integral flanges 3 and 4, respectively. The flange of member I, called the slide retainer, is threaded to receive a threaded clamping collar 8 that clamps over the flange of the other tubular member, called the spring retainer. The two retainers are spaced apart by a cylindrical window 1 seated in opposed annular grooves in the adjacent end faces of the retainers. The ends of the Window in the grooves.

retaining members I and 2. i v

The housing thus form'edhas an'axial passage,-

through it provided with a reduced inlet H and outlet I2 adapted to be connected into a line l3 that carries the fluid whose flow is to be indicated. The collar 6 is provided with circumferentially spaced openings M to permit the central portion of the passage to be viewed through the window. The left-hand end of the portion l6 of the axial passage in thespring retainer 2 is a little smaller in diameter than the main portion ll of the passage in the slide retainer I so that a radial shoulder IB is formed inside the window.

Slidably mounted in tubular member I is a passage-blocking slide 2| that fits rather loosely in passage I! so that fluid can leak past it, The

"a slide is hollow with open ends separated by 'a' transverse wall 22. That is, the inlet end of the slide is provided with an axial bore 23, while the outlet end of the slide is provided with a similar bore 24. The two bores are separated by wall 22.

When fluid is not flowing through the line the slide is held entirely inside the slide retainer by means of a coil spring 26 that engagegs its transverse wall 22 and the shoulder 2! formed by the outlet l2 of the passage. In this rear position the slide is not seen through the window, so it is known that fluid is not flowing through the housing. The fluid pressures at opposite ends of the slide balance by leaking past the slide. However, the moment fluid is withdrawn from the outlet of the housing passage a pressure drop across the slide is produced which results in the fluid at the inlet end of the housing pushing against the slide and thereby moving it forward against the resistance of the coil spring until its front end strikes shoulder i8, as shown in Fig. 3. This movement of the slide uncovers a plurality of radial holes with which it is provided, so that fluid can flow past the slide and thereby flow through the housing. Some of these holes 28 connect the inner or front end of slide bore 23 with a groove 29 around the outside of the slide, while the rest of the holes 3| are through the side wall of the slide at its front end. The groove is spaced such a distance from the front end of the slide that it is uncovered only when the slide is in its forward position against shoulder l8. That is, groove 29 and front slide holes 3| open into the space 32 between the inside of the window and the outside of the slide, which thereby forms a by-pass around the slide. Consequently, when the slide is seen through the win- 3 V V dow to be in its forward position, it is known that fluid is flowing through the housing. When the flow is shut off, the fluid pressure at the opposite ends of the slide becomes equal and the spring then pushes the slide back into theslide retainer V The disappearance of the slide from view through thewindowishows thai'ri flowlhasstopped?) According-to 'the provisions of the patent:statutes, I have explained the principle of my inven- 4 .7 provided with openings through it on opposite sides of said transverse wall, and a spring for holding the slide back between said observation opening and the passage inlet when fluid is not flowing through the housing but allowing the fluid behind the slide to push the slide forward into view thmugh the window whenfliiidi'is withdrawn from V the-massage outlea aid housing having why-pass for connecting the outer ends of said slide opention and have illustrated and described what Iillmlmgs on opposite ide of said transverse wall when nowrconsider to represent its best embodiment...

However I desire to have it understcodtliat," within the scope of the appendediclaim,,theeineritline, the housing having-Ian observation opening 20 extending g laterall fromrther'side'mfztherpassagw toi thez outside of: thei-housingz 'ia window sealed in" saidiopeninga a hollow slide disposed in rsaid; passage and having opens-endsiwithxartransversez wallsbetweemthezm thezsidawalror'theslide being 2,136,261;

the..-slide-Yis-, in its forward position, whereby the presence of the slide in its forward position indicatesrthat fifiitiiis fidwil'lg through the housing.

' FREDERICK N. WINDSOR.

REFERENCES CITED The eiollowings references are of record in the v file o,.this patent:

UNITED STA'EES PATENTS 

